This specification relates generally to query processing.
Internet travel search engines are used to plan travel. Users submit travel queries to Internet travel search engines and are presented with travel query results that satisfy the travel queries. The travel query results can include travel options that cover different aspects of travel, e.g., flights, hotels, car rentals, and activities.
Conventionally, users enter specific kinds of travel constraints, e.g., origin, destination, departure date, duration of stay, into corresponding fields in Internet travel search engine user interfaces in order to define a travel search query. However, these travel search engines are unable to return useful travel results for travel search queries that are not adequately defined by travel constraints.